Many electrical elements such as solenoid valves are provided with a plurality of outwardly projecting connector prongs to which a connector is attached to supply power to the element, receive sensor data from it, and/or communicate electrically with it. In German patent 3,507,696 filed 5 Mar. 1985 by F. Hafner such a system is disclosed having a rigid body provided with a plurality of connectors and here also incorporating some circuitry in the form of a printed circuit, electronic circuit elements, and a pilot lamp. A multiconductor cable extends laterally from the body which is typically a mainly plastic block. In order to protect the electrical connections and circuit elements from the elements, the body is fitted in a cap of a somewhat softer synthetic resin that has a seal skirt projecting from the face at which the connectors are exposed. For best fit this cup-shaped cap is formed directly around the body, for instance of a thermoplastic polyurethane elastomer.
This connector can therefore be fitted over the upstanding connector prongs of the solenoid valve, with the skirt engaging down around the connection region to seal it. The result when everything fits together perfectly is a good seal and a well protected connection. Due to the difference in materials between the body and the cap, however, these two parts are not physically bond together and can separate from each other. Thus with time, in particular as the plastic parts age, the skirt pulls away from the surface, leaving a crack into which water and foreign matter can enter to foul the contacts.